Reproducer for phonographs



Oct 20,

- c. G. HENSLEY REPRODUCER FOR PI IONOGRAPHS Original Filed June 30.; 9

till

P atented Oct. 20, 1925.

UNITED STATES PATIENT OFFICE.

CHARLES HENSLEY, OF BROOKLYN, NEW YORK.

BEPRODUCER FDR PHONOGRAPHS.

Application filed June 30, 1919, Serial No. 807,692. Renewed January 21, 1925.

To all whom it may concern:

Be it known that I, CHARLES G. HENSLEY, a citizen of the United States, and a resident of Brooklyn, in the city and State of\New York, have invented certain new and useful Improvements in Reproducers for Phonographs, of which the following is a specification. a

My invention relates to reproducers for phonographs and like devices wherein sound waves from a diaphragm are concentrated. Ihave embodied my invention in a phonograph reproducer butit will be obvious that it may be utilized as a telephone receiver by simply attaching a microphone so that its diaphragm occupies the position occupied by the diaphragm in the drawing herein.

In my Patent No. 1,379,407 dated May 24th 1921 I showed and described a novel reproducer for phonographs and the present invention is intended to utilize the features of that invention.

The present invention embodies a reproducer wherein the sound waves leave the outer portion of the diaphragm, as distinguished from those wherein the waves leave the center of the diaphragm and pass directly through. the throat of the reproducer.

Although in its broadest aspect my invention is not limited to the kind of material of which the instrument is made nevertheless the present device makes it possible to use wood without sacrificing brilliancy and clearness and instead of altering the quality of the tones. every tone may be reproduced withthe quality of the original sounds impressed on the record.

One object of my invention is to provide a reproducer wherein the sound waves leave the outer portion of the diaphragm and do not recross the latter and wherein the throat or reduced aperture through which the waves are directed my be made small in relation to the area of the diaphragm without placing too much back pressure or resistance upon the diaphragm and causing it to bend in such manner as to produce false loops and nodes. In order that the diaphragm may reproduce sound waves exactly like the original Waves it is necessary that the air pressure on one side of the diaphragm should be as near as possible like that on the opposite side'and any resistance to the movement of the air at one side of the diaphragm tends to resist the movement of the diaphragm and the unequal surface pressures cause the diaphragm to bend and form loops and nodes which are false or which are not represented by any waves in the record groove. The ideal condition has been diflicult to obtain owing to the fact that the air on one side of the diaphragm in reproducers is more or less confined and its movement is more impeded than the air on the open side of the diaphragm. It is also de-' sirableto have the throat or orifice through which the waves from the diaphragm pass as small as possible relatively to the area of the 'dia hragm for several reasons. One reason or this is, that the tones will be more sustained and all the waves recorded on the record will be reproduced because even a very slight movement of a large diaphragm will pu sate the air at a throat of small area, whereas, if the throat is relatively larger,'it requires a greater movement in the diaphragm to pulsate the air in the throat to maintain audible sound waves. llhe smaller the throat in relation to the diaphragm, other conditions being correct, the

1 more sustained are the sounds and the more accurate the reproduction. Another advantage of a relatively small throat is that tones oi high pitch as well as tones of low pitch may be accurately reproduced. In the present reproducer I am able to utilize a small'throat with a lar e diaphragm to attain the advantages re erred to and I am ableto do thiswithout introducing defects common to reproducers which deliver the sound waves from a throat which opens directly from the middle of the diaphragm.

In the resent reproducer there is no confusion 0 sounds regardless of how many different sounds are simultaneously recorded on the record; the tones are sustained; there is more expression, and in fact, the reproduction more accurately resembles the original sound waves.

Another advantage in the present device is that sound waves of every pitch are reproduced equally well. The high notes of the piccolo or vlolin, the very low tones of of the interme iate instruments are all accurately reproduced and the same is true of difi'erent voices. In the present reproducers it, is impossible to obtain the high treble and the low bass tones in the same reproducing instrument.

' The resent'invention has two main; fea tures, either of which may be separately used vthe tuba or large horn, as well as alto tones too but which when combined give the most perfect results. One feature is the shape of the sound space in the reproducer and the other is the graduated thickness of the walls of the members composing the reproducer, and these features will both be set forth in detail hereinafter.

In the drawing forming part of this application,

Figure 1 is an elevation of a reproducer embodying my invention,

Figure 2 is a longitudinal sectional View thereof,

Figure 3 is an elevation of the inner or core member,

Figure 4 is a sectional view taken on the line 4-4 of Figure 2, and

Figure 5 is a sectional view taken on the line 5--5 of Figure 2. a

Where the invention is embodied in a phonograph reproducer it includes an outer shell or casing, an inner member or core spaced therefrom to provide a sound passage, the diaphragm, and the stylus lever. In the drawing I have shown a casing or shell 1 and an inner member or core 2, both of which are preferably made of wood; the

diaphragm 3 the edge of which is clamped between the inner and outer washers 4, 5 by means of a metal ring 6; the stylus lever 7 fulcrumed at 8, and attached to the center of the diaphragm at 9; and a coupling member 10 adapted to be attached to the tone arm of a phonograph.

The shell 1 has a tapered bore 12 to form an air or sound chamber 11 and the core is tapered and it is held centered within the shell as by-means of pins 13, to form with the shell an air or sound space which is of annular-cross section the length of the core. The taper of the inner surface of the shell is not constant but instead, the taper is on a relatively wider angle at the diaphragm end considering the angle relatively to the plane of the diaphragm and on a relatively narrower or more acute angle near the throat end considering the angle relatively to the plane of the diaphragm. Preferably, the surface from'the larger end of.

the shell tapers on a'constant angle to about the point 14, this being the obtuse taper relatively to the plane of the axis of the bore, and from the point 14 to the throat or restricted discharge opening 15 the inner surface of the shell has a constant taper on a more acute angle relatively to the plane of the axis of the bore than the for ard part. The difference-in taper of these two preferably parallel with the forward portion 17 of the inner surface of the shell but the core extends beyond the point 14 so that its smaller end projects part Way into the space defined by the portion 18 of the shell. The forward end of the core is preferably fiat and parallel with the diaphragm and I have found that the closer the front of the core is to the diaphragm the better the results. I allow only sufficient space 19 to permit the diaphragm 3 to be vibrated for the longest sound waves recorded on any record. The smaller end of the core preferably has a fiat face 20 at right angles to the axis of the core and the small end of the core terminates inside the throat, preferably just beyond the point 1 1 as shown in the drawing.

As the diaphragm 3 is vibrated by movements imparted through the stylus lever 7 to the center of the diaphragm, the air between the latter and the wall 21 'of the core is alternately compressed and rarified. The greatest movement of the diaphragm is at the center and the wall 21 of the core is opposed to this portion so that a high degree of compression and rarification is attained and the compressions and rarificathrough the conical space 24 beyond the core and finally through the throat 15. The areaof a sound wave gradually decreases from the time it leaves the larger end of the core and it is most highly concentrated where it passes through the throat. I have found that where the. taper of the shell inside changes from a more obtuse to a more acute angle as above described that a more restricted throat may be used with a given size diaphragm and without making the tones hollow or tubby. On the other hand, I thus obtain sustained tones and I also reproduce sounds which are lost or are not reproduced in the ordinary form of reproducer. The best results are obtained when the core 2 is parallel with the forward portion 17 of the shell for the major portion of the length of the core. A wave leaving the diaphragm 3 in the space 19 passes around the core and out the throat and it doesnot return or recross the diaphragm and cause interference as in the ordinary reproducer in which latter. part of the wave is temporarily locked in the reproducer.

It will be noted that the shell 1 is shown that the core 2 has a hollow chamber 26 and 1 that the wall of the core is graduated in thickness being thinner at the larger end and gradually growing thicker toward the smaller end. The ideal condition is where the thickness at different portions of the shell and core is inversely as the area at each portion and circumferentially uniform. Given the thickness of thewall at A, and the internal diameter B at the same point, and given the diameter C of the throat then by reducing the formula A:C::X:B, we can determine what thickness the wall should be at the smaller end or at D. The

. thickness of the various portions-of the core may be determined inthe saint; manner; that is, the thickness should be approximately inversely as the area at any point. The core may be made by turning a frustro' conical body with the hollow chamber and the face cap 21 may be glued on the open end of the'core so that the space 26 in the core is closed. The grain of the wood in the cap 21' should be parallel or substantially parallel with the axis of the core in order that when this cap vibrates it will bend in concentric loops the same as the diaphragm.

here the walls of the shell or shell and core are tapered so that they are relatively thin where the area is greatest and relatively thick where the area isless, the sound waves areconcentrated without altering their character. Furthermore, it is possible to obtain in the same reproducer reproductions of tones of the highest as well as the lowest pitch and especially is it possible to reproduce tones of the tuba and bass VlOl which heretofore have not been reproduced except very faintly When sound waves are concentrated, as where they are reduced to pass through-the restricted throat of the reproducer, the action is substantially the reverse of amplification because the area of each sound wave is necessarily reduced. If the wave while undergoing concentration is broken up it tends to be divided into false partials andthis has been one of the main difiioulties in reproducers, especially where it has been attempted to use the larger diaphragms or to make the reproducer ofv wood.

As ll have set forth in my copending application Ser. No. 307,691, filed June 30, 1 19. the speed and amplitude of vibration of a body depends to a great extent upon area and thickness. If two boards of equal area but of dificrent thickness are struck alike the one of greater thickness willdvibrute faster than the thinner one and its amplitude of vibration will be less. If two boards of equal thickness but of different areas are struck alike the one of greater area will vibrate more slowly and its amplitude of vibration will be greater than the board of lesser area. In the present device the areas of the sound wavesare gradually reduced as they travel from the larger end of the core toward the throat. The walls are thinner where the sound waves are of larger area and the walls there have a greater amplitude of vibration. As the waves are gradually reduced in area they are reflected or propelled by thicker portions of the walls which have lesser amplitudes of vibration. The amplitude ofvibration of each portion of the wall is gradu ated according to the area and thickness and this graduation substantially corresponds to the gradual reduction in the area of the sound wave as it is concentrated or reduced in area. The result is that the waves are properly concentrated.

I have stated herein one method of arriving at the desired proportions but-my invention in its broad aspect is not limited to the proportions herein stated. The ideal condition is where the thickness of the walls is proportioned inversely as the area at difierent portions thereof.

It will be obvious that the present device may be used as a telephone receiver. In

that case the present diaphragm and stylus lever will be omitted and a microphone will be placed so that its diaphragm occupies the same position as the diaphragm in the drawing. The diaphragm of the microphone, operated electrically. will produce sound waves in the space 19 which will be concentrated the same as where the device is used a. reproducer. The term tapering as used in the following claims, except where modified by the term constant, is intended to cover any decrease in area whether regular or varying.

Having described my invention, what I claim is 1. A. reproducer comprisinga shell having a tapered space therein, a diaphragm at the larger end thereof and a core memher in said shell and spaced from said diaphragm and shell to provide an air or sound space, the inner surface of said shell tapering on a more obtuse angle relatively to the plane of the axis of the bore of the shell near the larger end of the shell and tapering on a more acute angle relatively to said plane near the smaller end of the shell.

2. A reproducer comprising a shell having a sound space therein, a diaphragm at one end of said sound space, and a frustroconical core in said shell, having its base opposed to said diaphragm, said core being spaced from said shell to provide a sound space of decreasing area, the innersurface of saidshell tapering on a more obtuse angle relatively to'the plane of the axis of the bore of the shell near the diaphragm end of the shell and tapering on a more acute angle relatively to said plane near the outlet end of said shell.

3. A reproducer comprising a shell having llO a sound space therein, a diaphragm at one end of said sound space. and a tapered core in said shell having its base opposed to and spaced from said diaphragm, said core being spaced from said shell to provide a sound space of decreasing area, the inner surface of said shell tapering on a more obtuse angle relatively to the plane of the axis of the bore of said shell, near the diaphragm end of said shell, and parallel with. said core, and said inner shell surface tapering on a more acute angle relatively to said plane near the outlet end of said shell.

4-. A reproducer comprising a shell having a sound space therein, a diaphragm at one end of said sound space, and a tapered core in said shell and having its base opposed to and spaced from said diaphragm, said core being spaced from said shell to provide a sound space of decreasing area, the inner surface of said shell tapering on a more 0btuse angle relatively to the plane of the axis of the bore of said shell, near the diaphragm end of the shell, and parallel with said core, and tapering on a more acute angle relatively to said plane near the outlet end of said shell, the. smaller end of said core terminating in said latter portion of the shell.

5. A reproducer comprising a shell having a sound space therein, a diaphragmat one end of said sound space, and a tapered core in said shell, having its base opposed to and spaced from said diaphragm, said core being spaced from said shell to provide a sound space of decreasing area, the inner surface of said shell tapering on a more obtuse angle relatively to the planeof the axis ofythe bore of the shell, near the diaphragm end of the shell andfor the major portion of the length thereof and parallel with said core, said inner surface tapering on a more acute angle relatively tosaid plane near'the-outlet end of said shell, the smaller end of said core terminating in said latter portion of the shell. i

6. A reproducer comprising a shell having a tapering sound space therein, a diaphragm at the larger end of said sound space, anda core in said shell, spaced from said shell and diaphragm to provide a sound space of decreasing area. said shell having a wall of graduated thickness.

7. A reproducer comprising a shell having a tapering sound space therein. a diaphragm at the larger end of said sound space, and a core in 'said shell spaced from said shell and said diaphragm to provide a sound space of decreasing area, said shell having a wall 'of graduated thickness with the thinner portion near the diaphragm end and the thicker portion near outlet end.

8. A reproducer comprising a shell having a tapering sound space therein, a diaphragm at the larger end of said sound space, and a core in said shell, spaced therefrom and from said diaphragm to provide a sound space of decreasin area, said shell having a wall graduatec in thickness substantially inversely relatively to the area at different portions thereof.

9. A reproducer comprising a shell having a tapering sound space therein, a diaphragm at the larger end of said sound space, and a hollow, tapering core in said shell spaced from said shell and said diaphragm to provide a sound space of decreasing area, said core having a wall of graduated thickness.

10. "A reproducer comprising a. shell having a tapering space therein, a diaphragm at the larger end of said space, and a hollow, tapering core in said shell and spaced from said shell and said diaphragm to provide a sound space of decreasing area, said core having a wall of graduated thickness with its thinner portion near the larger end of the core and its thicker portion near the smaller end thereof.

11. A reproducer comprising a shell having a tapering space therein, a diaphragm at the larger end of said space, and a hollow, tapering core in said shell and spaced from the shell and diaphragm to provide a sound space of decreasing area, said core having a wall graduated in thickness substantially inversely' relatively to the area at different portions of the core.

12. A reproducer comprising a shell having a tapering space therein and having its wall graduated in thickness, with the thinner portion near the larger end, a diaphragm at the larger end of said space, and a. hollow, tapering core in said shell and spaced from the shell and" the diaphragm to provide a sound space of decreasing area, said core having its wall graduated in thick?- ness with the thinner portion at the larger end thereof.

13. A reproducen comprising a. shell having a tapering sound space therein, the inner surface of said shell tapering on a more obtuse angle near the larger end and tapers mg on a more acute angle near the smaller end. the wall of said shell being graduated in thickness with the thinner portion near the larger end, a diaphragm at the larger end of,said space, and a hollow, tapering core in said shell and s aced from the-shell and diaphragm to provide a sound space of decreasing area. the. wall of said core being graduated in thickness with its thinner portion at the larger end of said core.

Signed at the city. county, and State of New York, this 27th day of June. 1919.

' CHARLES G. HENSLEY. 

